<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="../js/jquery.js"></script>
<script type="text/javascript">
	$(function(){
		$('#b1').click(function(){
			var $obj = $('ul li');
			
			//取下标对应处的dom对象，然后将这个dom对象封装成一个jquery对象
			var $o = $obj.eq(1);
			$o.css('font-size','60px');
			
			//返回dom对象或者jquery对象在类数组中的下标
			alert($obj.index($o));
		});
	});
</script>
</head>
<body>
	<ul>
		<li>item1</li>
		<li>item2</li>
		<li>item3</li>
	</ul>
	<input type="button" value="点击" id="b1"/>
</body>
</html>